ephemeral literal, relation heading, subs rel stored & lmdb 1GB map

2 files changed, 11 insertions, 6 deletions

diff --git a/lib/protocols/Relation.ml b/lib/protocols/Relation.ml
index b4cc4ec..9a6e739 100644
--- a/lib/protocols/Relation.ml
+++ b/lib/protocols/Relation.ml
@@ -18,15 +18,17 @@ let from handle = Handle.into handle (function Relation impl -> Some impl | _ ->
 let require handle = from handle |> Option.to_result ~none:(Error.not_a_relation ())
 let contains i tuple = Handle.invoke i (fun o -> o#contains tuple)
 
-let read relation =
+let heading relation =
   let open Utilities.Result in
   let* schematics = Handle.require Schematics.from relation in
   let* description = Schematics.describe schematics in
-  let* heading =
-    match description with
-    | Schematics.Relation heading -> Ok heading
-    | _ -> Error (Error.not_a_relation ())
-  in
+  match description with
+  | Schematics.Relation heading -> Ok heading
+  | _ -> Error (Error.not_a_relation ())
+
+let read relation =
+  let open Utilities.Result in
+  let* heading = heading relation in
   let* enumerable = Enumerable.require relation in
   let* cursor = Enumerable.enumerate enumerable in
   Fun.protect
diff --git a/lib/protocols/Relation.mli b/lib/protocols/Relation.mli
index 87e6ab2..47d1d3e 100644
--- a/lib/protocols/Relation.mli
+++ b/lib/protocols/Relation.mli
@@ -9,6 +9,9 @@ val from : Handle.t -> t Handle.interface option
 val require : Handle.t -> (t Handle.interface, Concepts.Condition.condition) result
 val contains : t Handle.interface -> Concepts.Tuple.t -> (bool, Concepts.Condition.condition) result
 
+(** the heading a relation describes itself with. *)
+val heading : Handle.t -> (Schematics.relation_description, Concepts.Condition.condition) result
+
 (** the heading and tuples of a relation, read whole. *)
 val read :
   Handle.t ->